Related to: https://github.com/neondatabase/neon/issues/2848
`pageserver_storage_operations_seconds` is the most expensive metric we
have, as there are a lot of tenants/timelines and the histogram had 42
buckets. These are quite sparse too, so instead of having a histogram
per timeline, create a new histogram
`pageserver_storage_operations_seconds_global` without tenant and
timeline dimensions and replace `pageserver_storage_operations_seconds`
with sum and counter.
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Describe your changes
Added a metric that allow to monitor tenants state
## Issue ticket number and link
https://github.com/neondatabase/neon/issues/3161
## Checklist before requesting a review
- [X] I have performed a self-review of my code.
- [X] I have added an e2e test for it.
- [ ] Do we need to implement analytics? if so did you add the relevant
metrics to the dashboard?
- [ ] If this PR requires public announcement, mark it with
/release-notes label and add several sentences in this section.
The code in this change was extracted from PR #2595, i.e., Heikki’s draft
PR for on-demand download.
High-Level Changes
- storage_sync module rewrite
- Changes to Tenant Loading
- Changes to Timeline States
- Crash-safe & Resumable Tenant Attach
There are several follow-up work items planned.
Refer to the Epic issue on GitHub:
https://github.com/neondatabase/neon/issues/2029
Metadata:
closes https://github.com/neondatabase/neon/pull/2785
unsquashed history of this patch: archive/pr-2785-storage-sync2/pre-squash
Co-authored-by: Dmitry Rodionov <dmitry@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
===============================================================================
storage_sync module rewrite
===========================
The storage_sync code is rewritten. New module name is storage_sync2, mostly to
make a more reasonable git diff.
The updated block comment in storage_sync2.rs describes the changes quite well,
so, we will not reproduce that comment here. TL;DR:
- Global sync queue and RemoteIndex are replaced with per-timeline
`RemoteTimelineClient` structure that contains a queue for UploadOperations
to ensure proper ordering and necessary metadata.
- Before deleting local layer files, wait for ongoing UploadOps to finish
(wait_completion()).
- Download operations are not queued and executed immediately.
Changes to Tenant Loading
=========================
Initial sync part was rewritten as well and represents the other major change
that serves as a foundation for on-demand downloads. Routines for attaching and
loading shifted directly to Tenant struct and now are asynchronous and spawned
into the background.
Since this patch doesn’t introduce on-demand download of layers we fully
synchronize with the remote during pageserver startup. See details in
`Timeline::reconcile_with_remote` and `Timeline::download_missing`.
Changes to Tenant States
========================
The “Active” state has lost its “background_jobs_running: bool” member. That
variable indicated whether the GC & Compaction background loops are spawned or
not. With this patch, they are now always spawned. Unit tests (#[test]) use the
TenantConf::{gc_period,compaction_period} to disable their effect (15db566).
This patch introduces a new tenant state, “Attaching”. A tenant that is being
attached starts in this state and transitions to “Active” once it finishes
download.
The `GET /tenant` endpoints returns `TenantInfo::has_in_progress_downloads`. We
derive the value for that field from the tenant state now, to remain
backwards-compatible with cloud.git. We will remove that field when we switch
to on-demand downloads.
Changes to Timeline States
==========================
The TimelineInfo::awaits_download field is now equivalent to the tenant being
in Attaching state. Previously, download progress was tracked per timeline.
With this change, it’s only tracked per tenant. When on-demand downloads
arrive, the field will be completely obsolete. Deprecation is tracked in
isuse #2930.
Crash-safe & Resumable Tenant Attach
====================================
Previously, the attach operation was not persistent. I.e., when tenant attach
was interrupted by a crash, the pageserver would not continue attaching after
pageserver restart. In fact, the half-finished tenant directory on disk would
simply be skipped by tenant_mgr because it lacked the metadata file (it’s
written last). This patch introduces an “attaching” marker file inside that is
present inside the tenant directory while the tenant is attaching. During
pageserver startup, tenant_mgr will resume attach if that file is present. If
not, it assumes that the local tenant state is consistent and tries to load the
tenant. If that fails, the tenant transitions into Broken state.
If there are any unexpected ERRORs or WARNs in pageserver.log after test
finishes, fail the test. This requires whitelisting the errors that *are*
expected in each test, and there's also a few common errors that are
printed by most tests, which are whitelisted in the fixture itself.
With this, we don't need the special abort() call in testing mode, when
compaction or GC fails. Those failures will print ERRORs to the logs,
which will be picked up by this new mechanisms.
A bunch of errors are currently whitelisted that we probably shouldn't
be emitting in the first place, but fixing those is out of scope for this
commit, so I just left FIXME comments on them.
Part of https://github.com/neondatabase/neon/pull/2239
Regular, from scratch, timeline creation involves initdb to be run in a separate directory, data from this directory to be imported into pageserver and, finally, timeline-related background tasks to start.
This PR ensures we don't leave behind any directories that are not marked as temporary and that pageserver removes such directories on restart, allowing timeline creation to be retried with the same IDs, if needed.
It would be good to later rewrite the logic to use a temporary directory, similar what tenant creation does.
Yet currently it's harder than this change, so not done.
Also get rid if `with_safekeepers` parameter in tests.
Its meaning has changed: `False` meant "no safekeepers" which is not
supported anymore, so we assume it's always `True`.
See #1648
* Add test for pageserver metric cleanup once a tenant is detached.
* Remove tenant specific timeline metrics on detach.
* Use definitions from timeline_metrics in page service.
* Move metrics to own file from layered_repository/timeline.rs
* TIMELINE_METRICS: define smgr metrics
* REMOVE SMGR cleanup from timeline_metrics. Doesn't seem to work as
expected.
* Vritual file centralized metrics, except for evicted file as there's no
tenat id or timeline id.
* Use STORAGE_TIME from timeline_metrics in layered_repository.
* Remove timelineless gc metrics for tenant on detach.
* Rename timeline metrics -> metrics as it's more generic.
* Don't create a TimelineMetrics instance for VirtualFile
* Move the rest of the metric definitions to metrics.rs too.
* UUID -> ZTenantId
* Use consistent style for dict.
* Use Repository's Drop trait for dropping STORAGE_TIME metrics.
* No need for Arc, TimelineMetrics is used in just one place. Due to that,
we can fall back using ZTenantId and ZTimelineId too to avoid additional
string allocation.
For better ergonomics. I always found it weird that we used UUID to
actually mean a tenant or timeline ID. It worked because it happened
to have the same length, 16 bytes, but it was hacky.
Merge batch_others and batch_pg_regress. The original idea was to
split all the python tests into multiple "batches" and run each batch
in parallel as a separate CI job. However, the batch_pg_regress batch
was pretty short compared to all the tests in batch_others. We could
split batch_others into multiple batches, but it actually seems better
to just treat them as one big pool of tests and use pytest's handle
the parallelism on its own. If we need to split them across multiple
nodes in the future, we could use pytest-shard or something else,
instead of managing the batches ourselves.
Merge test_neon_regress.py, test_pg_regress.py and test_isolation.py
into one file, test_pg_regress.py. Seems more clear to group all
pg_regress-based tests into one file, now that they would all be in
the same directory.
